A random sample of size n n\,n is taken from a population that is Normally distributed with mean 25 and standard deviation 4.
Find the smallest value of n n\,n for which the probability that the sample mean is greater than 27.5 is less than 1%.
284 exam-style questions on CCEA A Level Maths 4.5 Statistical distributions (A-level only), covering 4.5.1 Statistical distributions (A-level only) and 4.5.2 Statistical distributions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.